Seeing as I don't know what your options are I'll give an example in hopes that it'll help you understand them better.
"Her long hair was a flowing golden river"
A metaphor compares two things without using the words "like" and "as"
The example above compares the girl's hair to a "flowing golden river" but it never uses "like"or "as".
Another example could be, "The lake was a mirror"
Once again it is comparing the lake to a mirror with out "like" or "as"
Hope this helps a little. Let me know if you need anymore help.